Air-refrigerating machine



March 31. 1925.

l. LUNDGAARD AIR REFRIGERATING MACHINE Filed March 30, 19A22 2 SheetS-Sheet l UNIL A zo

March 3l. l 925.

l. LU NDGAARD Am REFRIGERATING MACHINE Filed March 30, 1922 2 Sheets-Sheet 2 INVENTOR A J mfrY Patented Mar. 31, 1925.

UNITED siATEs Ivan iNDGAARD, F HARTFORD, coiNEcrIoU'r, AssIGNon To 'rma AUTOMATIC REFRIGERATING COMPANY, OF NEW JERSEY.

HABTFO'RD, CONNECTICUT,` A. CORPORATIN OF AIR-BEFRIGERATING MACHINE.

Application ild March 30,1922. Serial lr'o. 548,218.

To lall whom it may concern: Be it linown that I, IvAR LUN'DGAARD, a

citizen of the United States', and a resident of Hartford, county of Hartford, -State' of I Connecticut, have invented certain new and useful Improvements in Air-Refrigerating Machines, of which the following is a specif ication. p

My invention relates primarily to air refrigerating machines of the ty e described in my Patent No. 1,240,862. n suchv maA` chilies, air is used as'the mediating fluid and is alternately compressed and expanded, heat being removed from the compressed air l5 by a cooling fluid and extracted from a duid to be refrigerated by the mediating air in the expanded condition. Theseoperations are carried out in a cylinder having a. compression piston and a shifter piston suitably operated to compress and expand the airin the desired cyc e while at the same time passing it through the heat exchangers and regenerator.

In order that the machine may give good results, it is necessary that the pistons and;

cylinder be properly lubricated without permitting oil to be carried by the 'swift air currents into the air passages or into the cold end where it` would tend to congeal,

due to the extremely low temperature there present. In any cylinder using a trunk piston there is a tendency to push oil up the cylinderwall along one side of the plston and down along the other sidewof the piston. This is due to the/variation in side pressure between the piston and cylinder wall resulting `from the angularity of the connecting rod or analogous part.

The thickness of a lilm of oil existing between rubbing surfaces and the movement 'of such a film are functions of the liberality of the oil supply and the pressures between the surfaces and the relative speed of the rfaces. In the event of oscillating motion under varying pressures of one surface against another, oil will in general be carried in the .direction of the movement taking place under the greatest average pressure. Thus, considering a trunk pist'on reciprocating in a vertical cylinder and receiving lubrication by splashl action from an actuating chamber below, that side of the piston which is under the greatest pressure of the cylinder,

during the up-stroke of the iston will carry oil upwards. The result o this is to cause accumulation of oil on the top of the piston. The object of the present invention is to provide means for preventing oil from getting into the cold end or on top of the piston, while. at the same time insuring proper 60 lubrication. A

To attain this object, I rovide first, a chamber. in which oil pushe up by the piston may accumulate. second, a passage through which the oilO may be carried from the chamber to some point of thcircumference of the piston other than that at which' the oil has been pushed up and where it may pass down. The chamber and passage are so located and formed that they are not subject to detrimental effects of the air currents in the cylinder. This chamber may be eithcrin the iston or the cylinder and in either case is ocated attlie upper limit of contact surface of the member ini-which itis located, an extension of the piston running in close proximity but not touching 'the wall of the cylinder performing the function of protecting the oil in the chamber from the air passing into and out In order that my invention may be readily understood, itl is described in connection with the accompanying drawings, in which Figure 1 is a vertical se'ction through the 85 two cylinders of m'y air refiigerating machine. -A f Figure 42 is an enlarged section of the compression piston of the machine of Figure 1, showing the adjacent parts of t,lie',3 I

cylinder.

Figure Iis a view showing a modification of the piston wherein the oil groove "is in the piston.l .i

Referring more particularly to the drawings, the compression piston 1, Figure "1, A is shown in its lowest position and the compreion piston 2 is shown in 'its liest position. The shifter piston 3 is at its ighest position. Shifter piston 4 has reached 1 la position from which it follows compression piston 2 downward for a certain distance. -The compression pistons are driven through links 5, walking-beam 6, connecti rod 8, and crank-pin 9, from shaft'lO. The shifter piston 3 is driven by rod 11 which yzo passes through a bushing 12 in piston 1 and is guided at its lower end inguide 13. This rod is actuated by cam 14 through roller 15, lever 16, and a link 26 connecting the end ofv lever 16 with the spring seat 17, which" is attached to the rod 11. The spring 18 serves to hold the cam roller 15 on the cam 14 and drives the piston 3A in one direction. Shifter lar manner.

The rod' 11 and um' p'ison 1 :are lubricated by splash lubrication supplied by the connecting rod 8 which dips into the oil in thecrank-caseat each revolution. The

oil level is indicated by the dotted line 19 pushed up byzthe' piston to flow around the piston to a point where it will-he carried down again to the crank case. If, for example, we assume that the arrow 22 (Figure 2) represents the direction of side thrust on the up-stroke and arrow 23 the direction of side thrust on the down-stroke,` oil will be carried up on the left side of the piston and down on the right side. The exact points where oil will be carried up or down depend on the driving mechanism of the piston and the way in which the gas pressure above and below .the iston varies. 'The actual dill'erence of fluid pressure between the spaces above and below the piston has little electon the amount of oil pushed up or down-by the -piston except as it.determines the side pressure on the piston. Further, in certain types of engines, the side pressure mayv-ibe always toward one side, with variation of intensity only. In all these cases, the 'rroove 20 serves to distribute the oilpusltied up, to some point where it will pass down again.

It is to be noted that recess 27 formed at the upper end ofthe bushing 12 in the piston l, operates on the same principle as groove 20 and serves to prevent oil from being carried to the top fof the'piston by the action of shifter rod 11 sliding in piston bushing 12.

Using the construction. shown in Figure 1, I have found that, after -many hours running, ho bil is to be found on top of the piston, or in the air assages.

In Figure 3," a modified form of piston 1 is shown.v The annular oil groove 20 is turned in the outside wall of the piston toward its upper end andxthe portion 25 of the piston above the groove 20 has clearance between it and the cylinder wall 21.

The ,amount of oil supplied to the piston may be varied by the use of -a thin sleeve piston 4 operates in a simi- 24 (Figure 2) attached to the lower end of the piston 1. .The function of this sleeve is to prevent some of thc oil splashed from stri fing the cylinder and piston. By varying `the length of the sleeve, this effect can be varied.v

As Shown in Figures 2 and 3, the pistons are at their lowest positions. Their highest positions are indicated by dotted lines.

It is to be noted that the location of the chamber for receiving'the surplus oil is important in that it must always. be at the upper limit of the contacting surfaces and yet not high enough to overflow the top of the piston or into ports or clearance spaces Where it might be affected by the air currents. There being no contacting surfaces above the oil chamber there will be ndv pumping up of oil above the chamber and there being a clearance betweenthe upper part of the piston and the cylinder wall this part of the piston will not pump oil so that the chamber is as high as the oil can get. It follows, therefore that the non-contacting upper extension of the piston will act as a shield to prevent the air currents in the cylinder from sweeping up the oil and carrying it where it is not wanted. I am aware that it is not new 4to provide oil grooves either in the piston or in the cylinder for effecting a distribution of the oil but there have always been contacting surfaces above even the top oil groove so that pumping of oil into the top of the piston or into ports or clearance spaces has not been avoided.

Although my invention is described in connection with air-refrigerating machines, it is useful in connection with other types of reciprocating engines, especially those having vertical cylinders and using a gaseous fluid. Other modifications are possible and I do not limit myself to the embodiment shown herein.

I claim 1. Cylinder and piston construction cornprising a cylinder, a piston reciprocablc therein, an oilpassage in one of said members extending from one portion of the piston circumference to another, said cylinder and piston having a construction to at all times restrict communication' with said passage from the space above the piston while avoiding contact between the cylinder and piston above said passage. j;

2. Cylinder and piston construction'icomprising a cylinder, a piston reciprocable in said cylinderl means for supplyin Iluid lubricant for'said'pis'ton, an oil c amber at the upper limit ofthe contacting surface of `said, plston and cylinder, said oil chamber leadmg from one side of the cylinder to the o posite side, the piston and cylinder coexten ing above the oil chamber with clearance to prevent contact and thus form il zneg-iibove the oil chamber that is nonchamber having a cylindrical extension, said fabiiciite-angl protected from freely movextension being of less diameter than the 10 mggll's. f cylinder suflicicnt to prevent contact and 3. Cylinder and piston construction comthe outlet for oil fromthe oil chamber limrising -a." ylin leij,-:L'piston rcciprocable in` ited to the space between the contacting vSaid cylinder, a circumferential oil chamsurfaccslothe cylinder and piston.

berlin the;- piston at the upper limit of its Contacting s'urce, 4the piston above the oil i IVAR LUNDGrAAR-D.v 

